1. Field of the Invention
The present invention relates to a self-propelled colonoscope. That is a self-propelled colonoscope which can be easily inserted into the colon and used for observation, photographing, biopsy and surgical operation of the colon without causing pain to a patient.
2. Description of the Related Art
Examination using an endoscope is widely used for observing, photographing a part of the examination, taking specimen from a lesion to ascertain if a tumor is malignant, removing when the tumor is malignant, observing other pathological and physiological conditions and processes and removing foreign body. An endoscope is also useful in the examination of a colon. In the conventional method of examining a colon using an endoscope, the endoscope must be manually inserted into the colon by pushing it with the hands, even though various other techniques can be applied. Therefore, it frequently occurs that a patient strongly complains of abdominal pain and distension because the colon is extended or excessively dilated and insertion of the endoscope into the colon must sometimes be stopped. Furthermore, it is not unusual for the colon to bleed and be accidentally perforated. In particular, these complaints frequently occur in cases of adhesion of the intestine from a previous abdominal operation. Therefore, a highly standardized technic is required for inserting an endoscope into a colon, and particularly for smoothly inserting the endoscope through the sigmoid colon and into the descending colon and ascending colon. Insertion of an endoscope through the splenic flexure, the transverse colon, the hepatic flexure or an adhesion part caused by previous operation is also accompanied with difficulty. Because of these reasons, a colonoscopy is only performed by a few doctors who are versed in the manipulation of a colonoscope. It is also considered that a patient has to endure some pain and discomfort.
As a colonoscope which can be inserted easily, safely and rapidly without causing pain to a patient, the present inventor proposed in Japanese Patent Application Laid-Open No. Heisei 8(1996)-38416 a self-propelled colonoscope which is equipped with endless belts in the area ranging from a position of 3 to 10 cm from a distal end of a flexible part to a control part and can be smoothly inserted into the colon by driving the endless belt by a driving mechanism located at the control part. This self-propelled colonoscope can be inserted easily without giving pain to a patient. However, further improvement in the property for insertion and decrease in the possibility of causing bleeding in the colon and giving pain to a patient has been desired.